Noémie Ehstand

A fisherman pulls on his net and listens to it ring. Each strand quivers in its own way, but before a strong tug, all the strands begin to vibrate in unison. So it is with complex systems: before a sharp state jump, the individual parts suddenly start to oscillate in concert, and that synchrony betrays the coming jump.

Over the warm waters of the Indian and Pacific Oceans, a giant wave of moist air is born every month or two. It creeps eastward at a pedestrian pace, about five meters per second, dragging bands of downpours and droughts behind it. Meteorologists call it the Madden–Julian Oscillation MJO.